The latest web apps update from Mozilla Labs, available as an add-on for Firefox, gives the experimental project a new look and helps individual apps communicate with one another.

Web apps now appear in a tray at the bottom of the browser window. Once opened, they become pinned tabs with no URL bar, giving them a more app-like feel. Mozilla also wants to aid app discovery by letting web developers notify visitors when an app is available — kind of like the App Store link that appears when you visit Yelp’s mobile website.

The bigger improvement in this release is “Web Activities.” This is basically a calling service for web apps to pass data back and forth. So for instance, if you’re using an online photo editor such as Pixlr and want to import an image from Dropbox, neither service would have to support the other specifically. The Web Activities calling service would handle the file transfer.

Mozilla says it’s working with Google’s Chrome team on the concept. Native smartphone apps can already communicate through standardized methods — Android has an intents system, as TechCrunch’s Jason Kincaid points out, while iOS audio apps can use third-pary methods such as Sonoma AudioPaste — so it makes sense for web apps to follow along.

Hopefully, these features will do a better job of justifying the existence of web apps in the first place. When Google launched the Chrome Web Store last December, critics dismissed these apps as glorified bookmarks. That’s not necessarily a bad thing, but unless web apps evolve, they’ll never be viewed as a vital part of the web browsing experience. I’m glad Mozilla and Google are working on that.